Parachute architecture for low-altitude VTOL aircraft

ABSTRACT

In an embodiment, a system to deploy a plurality of parachutes includes a plurality of parachute canopies each packed in a canister, a plurality of rockets adapted to extract an associated canopy from the canister, and a controller. The controller is configured to determine that an aircraft is at least one of: in a hover mode of operation and a forward flight mode of operation. In response to the determination that the aircraft is in the hover mode of operation, the controller applies a hover deployment sequence including by instructing the plurality of parachutes to deploy substantially simultaneously. In response to the determination that the aircraft is in the forward mode of operation and above a threshold airspeed, the controller applies a forward deployment sequence including by instructing the plurality of parachutes to deploy in a predefined sequence.

CROSS REFERENCE TO OTHER APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/718,173 entitled PARACHUTE ARCHITECTURE FOR LOW-ALTITUDE VTOLAIRCRAFT filed Aug. 13, 2018 which is incorporated herein by referencefor all purposes.

BACKGROUND OF THE INVENTION

New types of aircraft are being developed that take off and landvertically. While airborne, these new types of aircraft can hovermid-air, or fly forwards along some path. These new types of aircraftalso fly relatively low to the ground. New types of safety devices whichare specifically designed for such aircraft would be desirable.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the invention are disclosed in the followingdetailed description and the accompanying drawings.

FIG. 1 is a flowchart illustrating an embodiment of a process to performa deployment sequence associated with hovering or one associated withforward flight above a certain airspeed depending upon the aircraft'sstate.

FIG. 2 is a diagram illustrating an embodiment of a low-altitude,vertical takeoff and landing multicopter.

FIG. 3 is a diagram illustrating an example of a flight path whichincludes hovering and forward flight.

FIG. 4 shows vertical speed of a vehicle over time obtained in someembodiments of the present disclosure.

FIG. 5 shows vertical speed of a vehicle over time obtained in a typicalsystem.

FIG. 6 is a diagram illustrating an embodiment of a 3-parachute systemembedded behind the cockpit of a multicopter.

FIG. 7A shows the example multicopter in a hovering state as the threeparachutes are simultaneously deployed.

FIG. 7B shows the system after the three parachutes are fully deployed.

FIG. 8A shows the system when a first parachute begins to deploy.

FIG. 8B shows the system after the first parachute has fully deployed.

FIG. 9A shows the system when a drogue begins to deploy.

FIG. 9B shows the system when the drogue is fully deployed.

FIG. 9C shows the system when the drogue separates from the rest of thesystem and additional parachutes begin deploying.

FIG. 10 is a diagram illustrating an embodiment of a parachutedeployment system.

FIG. 11A is a diagram illustrating an embodiment of a parachutedeployment system in a stowed state.

FIG. 11B is a diagram illustrating an embodiment of a parachutedeployment system following rocket deployment.

FIG. 11C is a diagram illustrating an embodiment of a parachutedeployment system wherein the parachute is towed via a tow line.

FIG. 11D is a diagram illustrating an embodiment of a parachutedeployment system during release of a lower parachute line, canopy line,and/or suspension line restrainer.

FIG. 11E is a diagram illustrating an embodiment of a parachutedeployment system wherein the tow load imparted by the rocket istransferred to a release line.

FIG. 11F is a diagram illustrating an embodiment of a parachutedeployment system wherein the parachute is separated from a rocket.

FIG. 12 is a diagram illustrating an embodiment of a parachutedeployment system.

FIG. 13 is a flow diagram illustrating an embodiment of a process todeploy a parachute, including release of a rocket.

FIG. 14 is a flow diagram illustrating an embodiment of a parachutedeployment process with load-bearing context.

FIG. 15A is a diagram illustrating an embodiment of a release comprisinga latch and a cutter.

FIG. 15B is a diagram illustrating an embodiment of a release wherein arelease system restrainer is broken.

FIG. 15C is a diagram illustrating an embodiment of a release wherein alatch restrainer is broken.

FIG. 15D is a diagram illustrating an embodiment of a release wherein alatch is open.

FIG. 15E is a diagram illustrating an embodiment of a parachutedeployment system following separation of the parachute and a rocket.

FIG. 16 is a diagram illustrating an embodiment of a cutter with achannel to thread the latch restrainer through.

FIG. 17 is a flow diagram illustrating an embodiment of a process toopen a release.

FIG. 18A is a diagram illustrating an embodiment of a soft pin releaseassembly.

FIG. 18B shows another view of an embodiment of a soft pin releaseassembly.

FIG. 19A is a diagram illustrating an embodiment of a parachutedeployment system including a line constrainer associated with a firstarea, A1.

FIG. 19B is a diagram illustrating an embodiment of a parachutedeployment system including a line constrainer associated with a secondarea, A2.

FIG. 20A is a diagram illustrating an embodiment of a rectangular lineconstrainer.

FIG. 20B is a diagram illustrating an embodiment of a circular lineconstrainer.

FIG. 21A is a diagram illustrating an embodiment of a parachutedeployment system following rocket deployment.

FIG. 21B is a diagram illustrating an embodiment of a parachutedeployment system while the parachute is towed via a tow line.

FIG. 21C is a diagram illustrating an embodiment of a parachutedeployment system during release of a lower parachute line restrainer.

FIG. 21D is a diagram illustrating an embodiment of a parachutedeployment system following the shifting of a load from a first loadpath to a second load path.

FIG. 21E is a diagram illustrating an embodiment of a parachutedeployment system following separation of the parachute from the rocket.

FIG. 21F is a diagram illustrating an embodiment of a parachutedeployment system with a fully deployed parachute.

FIG. 22A is an exploded view illustrating an embodiment of a parachutedeployment system with locking stows.

FIG. 22B is a diagram illustrating an embodiment of a parachutedeployment system with locking stows when a rocket is initiallydeployed.

FIG. 22C is a diagram illustrating an embodiment of a parachutedeployment system with locking stows during extraction.

FIG. 22D is a diagram illustrating an embodiment of a parachutedeployment system with locking stows at the later stages of extraction.

FIG. 22E is a diagram illustrating an embodiment of a parachutedeployment system with locking stows after the rocket separates from theparachute.

FIG. 23 is a flow diagram illustrating an embodiment of a process tomanufacture a parachute deployment system including a line constrainer.

FIG. 24 is a diagram illustrating an embodiment of a conventionalparachute in a conventional packed state.

FIG. 25 is a diagram illustrating an embodiment of a parachute in asymmetrically packed state.

FIG. 26 is a diagram illustrating an embodiment of a soft pack containerfor a parachute.

FIG. 27 is a diagram illustrating an embodiment of a soft pack containerfor a parachute in a packed state.

DETAILED DESCRIPTION

The invention can be implemented in numerous ways, including as aprocess; an apparatus; a system; a composition of matter; a computerprogram product embodied on a computer readable storage medium; and/or aprocessor, such as a processor configured to execute instructions storedon and/or provided by a memory coupled to the processor. In thisspecification, these implementations, or any other form that theinvention may take, may be referred to as techniques. In general, theorder of the steps of disclosed processes may be altered within thescope of the invention. Unless stated otherwise, a component such as aprocessor or a memory described as being configured to perform a taskmay be implemented as a general component that is temporarily configuredto perform the task at a given time or a specific component that ismanufactured to perform the task. As used herein, the term ‘processor’refers to one or more devices, circuits, and/or processing coresconfigured to process data, such as computer program instructions.

A detailed description of one or more embodiments of the invention isprovided below along with accompanying figures that illustrate theprinciples of the invention. The invention is described in connectionwith such embodiments, but the invention is not limited to anyembodiment. The scope of the invention is limited only by the claims andthe invention encompasses numerous alternatives, modifications andequivalents. Numerous specific details are set forth in the followingdescription in order to provide a thorough understanding of theinvention. These details are provided for the purpose of example and theinvention may be practiced according to the claims without some or allof these specific details. For the purpose of clarity, technicalmaterial that is known in the technical fields related to the inventionhas not been described in detail so that the invention is notunnecessarily obscured.

Various embodiments of a parachute system are described herein. First, aprocess for performing a deployment sequence using a parachute system isdescribed. These parachute systems are designed for certain types ofaircraft. For context, an example aircraft is described next. Then, oncethe example aircraft is described, various embodiments of the parachutesystem which satisfy the specific constraints of the exemplary aircraftare described.

FIG. 1 is a flowchart illustrating an embodiment of a process to performa deployment sequence associated with hovering or one associated withforward flight above a certain airspeed depending upon the aircraft'sstate. In some embodiments, the process is performed by the controller(e.g., a control board) of the parachute system.

At 100, an indication to deploy the parachute system is received. Forexample, the main flight computer or controller may generate a signalwhen it determines that a crash or hard landing is imminent and theparachute system should be deployed, or that a critical fault hasoccurred. Any appropriate technique to detect an emergency or failuremay be employed. This signal may be sent from the main flight computerto the parachute controller, or may be manually commanded by the pilot.A command to deploy may also occur if the parachute controllerdetermines that the main flight computer is unresponsive.

At 102, it is determined if the aircraft is hovering or in forwardflight above a certain airspeed. For example, in addition to thedeployment indication received at 100, the main flight computer may alsosend one or more signals from which the hovering versus forward flightstate may be determined. In one example, the signal exchanged is abinary signal where 0=hovering and 1=forward flight above a certainairspeed. Alternatively, the main flight computer may send stateinformation (e.g., position, velocity, acceleration, or othermeasurements) and the parachute may decide for itself which state theaircraft is in. In some embodiments, an estimate or sensor measurementof the airspeed is received at step 102.

If it is determined at step 102 that the aircraft is in a hovering mode(e.g., because the aircraft's forward speed and/or lateral speed issubstantially zero, if the airspeed measurement or estimate is below acertain airspeed, etc.), then the parachute system is deployed using adeployment sequence associated with hovering at 104.

In one example of a deployment sequence associated with hovering, all ofthe (e.g., individual) parachute canisters are ignited or deployed atthe same time. See, for example, FIG. 7A and FIG. 7B. FIG. 7A shows theexample multicopter in a hovering state (700) as the three parachutes(702) are simultaneously deployed. FIG. 7B shows the system after thethree parachutes are fully deployed.

Returning to FIG. 1, if it is determined at 102 that the aircraft is ina forward flight mode above a certain airspeed, then the parachutesystem is deployed using a deployment sequence associated with forwardflight. See for example, FIG. 8A and FIG. 8B. FIG. 8A shows the systemwhen a first parachute begins to deploy. The parachute can begin todeploy (802 a) when a multicopter (800) is in a forward flight above acertain speed. For example, in FIG. 6, the rearmost parachute (600 b)may be deployed first because the angle of the rearmost parachute pointsmore downwind than the other two parachutes (i.e., its angle of attackis smaller), increasing its chances of successful inflation. FIG. 8Bshows the system after the first parachute (802 b) has fully deployed.After the vehicle has stabilized under the first parachute, the twoforward rockets are ignited, their trajectories designed to clear thevertical axis and canopy under which the vehicle is hanging. The anglesof the forward two rockets may be chosen such that the rockets travel tothe left and the right of the inflated canopy when ignited after thefirst parachute and vehicle have stabilized, minimizing chances ofstriking the inflated canopy. These angles may be chosen according tothe designed vehicle hang angle under one canopy and the allowableoscillation of a single parachute. The angle of the rearmost rocket,forward two rockets, and/or central axis of the three rocket vectors mayalso be designed to maximize chances of successful fast inflation bothin forward flight and in hover. Lower angle of attack at high speed(angling toward the rear of the vehicle) maximizes chances of normalinflation at high speed, but angling vertically reduces time anddistance required for inflation when parachutes are deployed in hover.As an alternate and faster method of deploying the two forwardparachutes, the airstream due to the forward movement of the multicopterwill cause the first parachute to be pulled slightly behind themulticopter. This creates space above the cluster of parachutes so thatthe second and third parachutes (804) can be deployed. This sequentialdeployment of the parachutes applies deceleration loading over a longeramount of time and prevents simultaneous parachute openings, reducingpeak loading on the pilot at high speed. Sequential deployment alsohelps to avoid entanglement of the lines and/or canopies if all threeparachutes were deployed simultaneously at high speed. In someembodiments, some other sequence (e.g., two at first, then the third;each deployed separately; etc.) is used. The following figure shows anexample of an aircraft in which a process to perform a parachutedeployment sequence can be performed.

FIG. 2 is a diagram illustrating an embodiment of a low-altitude,vertical takeoff and landing multicopter. In this example, multicopter200 has an open-air cockpit and could be designed to spend a significantportion of its flight time below a few hundred feet. This is arelatively low altitude compared to other types of aircraft and (as willbe described in more detail below) if a parachute system is used withsuch an aircraft, the parachute's canop(y/ies) should fully inflatequickly in order to minimize any initial vertical drop before theparachute system engages and slows the descent of the aircraft. Incontrast, an aircraft that flies at higher altitudes can tolerate moreof a vertical drop before the canop(y/ies) inflate and slow theaircraft's descent.

The multicopter in this example has 10 rotors (202) which rotate aboutsubstantially vertical axes. This exemplary aircraft has booms (204) andfloats (206) to which the rotors are attached. The booms and floats donot collectively produce enough aerodynamic lift for wing-borne flight,even if the aircraft is flying forwards at a relatively high speed. Toput it another way, the exemplary aircraft does not have wings andcannot glide to the ground in the event of a complete loss of power orother emergency. For this reason, a parachute system or other safetydevices which can be deployed in an emergency would be desirable.

The following figure shows an example flight of the exemplarymulticopter shown here.

FIG. 3 is a diagram illustrating an example of a flight path whichincludes hovering and forward flight. In this example, multicopter 300begins on the ground. In this example flight, the multicopter takes offvertically and ascends vertically. As the multicopter gets closer tosome desired cruising altitude, the multicopter slows its verticalascent until it comes to a stop, hovering mid-air (302).

From the hovering position (302), the multicopter transitions fromhovering mode or style of flight to a flying forward mode or style offlight (e.g., where the multicopter flies within some 2D plane at arelatively constant altitude). In this example, the aircraft has amaximum speed on the order of 55 knots. As described above, themulticopter is designed to fly at relatively low altitudes and so thiscruising altitude may be relatively low compared to other types ofaircraft (e.g., with enclosed and/or pressurized cockpits).

Once the multicopter gets close to some desired destination, themulticopter comes to a forward stop and hovers in the air (304). Themulticopter then descends vertically to perform a vertical landing andlands on the ground (see multicopter 306).

Due to the relatively low flying altitude of the multicopter, aparachute system which is used in the exemplary aircraft shouldpreferably deploy quickly and/or with very little vertical drop beforefull inflation of the canop(y/ies) slows the descent of the aircraft. Toput it another way, there is very little margin for any vertical dropbefore the parachute system needs to slow the aircraft down in order toavoid a high-velocity impact (unsafe impact velocity). For this reason,in some embodiments, the parachute system includes (e.g., threeindependent) ballistic parachutes where the rockets help to inflatetheir respective canopy quickly (e.g., one or more rockets per canopy,pulling upwards and outwards). In various embodiments, the individualparachutes include a variety of features, techniques, and/ortechnologies to inflate the canopies quickly and/or minimize any dropbefore the canopies fully inflate.

The parachute system with ballistic parachutes (also sometimes calledlow-altitude ballistic recovery system) disclosed here limits maximumdownward speed during extraction and inflation (from hover) such thatthe impact is considered safe when the parachute is deployed from anyaltitude. That is, downward vehicle speed does not exceed an unsafeimpact velocity. The unsafe impact velocity is a value consideredunsafe. For example, at or exceeding an unsafe impact velocity, if thevehicle strikes an object or the ground, the vehicle occupants might beinjured or killed. FIG. 4 shows vertical speed of a vehicle over timeobtained in some embodiments of the present disclosure. FIG. 5 showsvertical speed of a vehicle over time obtained in a typical system. Eachof the numbered circles corresponds to one of the states below:

-   -   1) Vehicle accelerates in freefall    -   2) A fault is detected and rocket(s) extract canop(y/ies) to        begin slowing the vehicle    -   3) Vehicle begins to decelerate because canop(y/ies) begin to        inflate    -   4) Canop(y/ies) are fully open to limit the maximum speed of the        vehicle, and vehicle continues to decelerate    -   5) Vehicle reaches steady-state descent velocity under inflated        canop(y/ies)

In embodiments of the low-altitude parachute system disclosed here, thevehicle vertical speed never exceeds an unsafe impact velocity as shownin FIG. 4. By contrast, a conventional system such as the one shown inFIG. 5 permits the vehicle vertical speed to exceed an unsafe impactvelocity. This is because a conventional system is typically optimizedfor higher speeds. When the conventional system is used in alow-altitude and/or low-speed condition, the system is slow to inflatethe canop(y/ies) so that vehicles can exceed an unsafe impact velocitybefore the canop(y/ies) are fully inflated to slow the fall of thevehicle.

Another desired characteristic of a parachute system for the exemplaryaircraft shown here is that the canopies are able to properly and/orquickly inflate in a variety of (e.g., crosswind, cross flow, orairspeed) conditions. As shown in this example flight, the exemplarymulticopter has at least two different flying modes: a hovering mode anda forward flight mode (e.g., between 302 and 304). The vertical takeoff(e.g., between 300 and 302) and vertical landing (e.g., between 304 and306), for the purposes of explaining the parachute system embodimentsdescribed herein, fall under hovering mode. When the multicopter is inhovering mode, there is no front-to-back or side-to-side movement withinthe 2D plane defined by the longitudinal axis and the transverse axis.As such, there is very little crosswind due to the aircraft's movementin that 2D plane. This is one condition or situation in which theparachute system may be deployed.

In contrast, when the multicopter is in forward flight mode, there willbe a relative airspeed due to the multicopter's movement (e.g., forwardsin the example of FIG. 3). This is another condition or situation inwhich the parachute system may be deployed. In other words, it would bedesirable if a parachute system used in the exemplary aircraft coulddeploy under both of these conditions.

FIG. 6 is a diagram illustrating an embodiment of a 3-parachute systemembedded behind the cockpit of a multicopter. The rotors (202), booms(204), and floats (206) shown in FIG. 2 are not relevant to thisdiscussion and as such are not shown in this figure. In this example,there are three parachute canisters (600 a-600 c), each with its ownpacked canopy. Each of the canopies is extracted by its correspondingrocket motor (602 a-602 c). A controller is communicatively coupled tothe rockets and/or parachutes to decide when and/or how to deploy theparachutes. The controller can perform a process such as the one shownin FIG. 1 to deploy the parachutes. As described above, the exemplaryaircraft flies relatively close to the ground and using ballisticparachutes helps to minimize canopy inflation time and/or vertical dropbefore the parachute system slows the descent of the aircraft.

In this example, the parachute canisters (600 a-600 c) are arranged in acluster (e.g., instead of a single parachute) which helps with inflationtime while still slowing the descent of the aircraft. For example,suppose a single, large canopy with the same effective diameter as thethree smaller canopies was used instead. The larger canopy would requiremore time to inflate while still offering roughly the same decelerationperformance as the three smaller canopies combined. Furthermore, withmultiple canopies, this eliminates a single point of failure (e.g., ifone of the canopies fails to open, the other two canopies will probablyopen) whereas if the single, large canopy fails to open, there is nobackup parachute. Naturally, the diameter of the canopies may beselected so that even if one of the canopies fails to open, the descentwill still be survivable. A more detailed example of a parachutecanister (600 a-600 c) is described below.

In various embodiments, the propellant in the rocket motors (602 a-602c) is ignited using power cartridges, pyrotechnic assemblies, igniters,or initiators. These methods of ignition may be desirable because thereis a relatively short lag from flight computer initiation signal toigniter and rocket ignition, both of which (further) help to minimizecanopy inflation time and/or vertical drop.

Each of the canopies in the parachute canisters (600 a-600 c) isconnected by a separate (e.g., independent) line (not shown) to aconnection point (604) behind the pilot's headrest. These separate lineshelp to prevent single points of failure. The connection point is partof the frame of the fuselage (e.g., which also includes the pilot'sseat) to help ensure that the pilot and the fuselage stay with theparachute.

As described above, the parachute system may be deployed when theaircraft is hovering or when the aircraft is flying forwards above acertain airspeed. In some embodiments, to better handle the differentconditions, two different deployment processes and/or techniques areused in these modes. FIG. 1 describes an example of this.

In some embodiments, a drogue parachute is deployed prior to thedeployment sequence shown in FIG. 8A and FIG. 8B. FIG. 9A to FIG. 9Cshow an example of a drogue parachute deployment. FIG. 9A shows thesystem when a drogue begins to deploy. FIG. 9B shows the system when thedrogue is fully deployed. FIG. 9C shows the system when the drogueseparates from the rest of the system and additional parachutes begindeploying.

The drogue parachute 902 a is separate from the main canop(y/ies) and isconfigured to operate above certain airspeeds and altitudes to slow andstabilize the vehicle, limiting high-speed opening shock, and increasingthe probability of successful deployment of the main canop(y/ies).Sometimes, after a first main canopy deploys, the vehicle may be sounstable (the limits of oscillation of the vehicle in steady state aresuch) that deploying subsequent main canopies would interfere or hit thefirst main canopy. This may cause the main canopies to not be able tooperate sufficiently to slow the vehicle to a safe state. A drogueparachute puts the vehicle into a state optimal for the three mainparachutes to be deployed.

In various embodiments, a drogue parachute is deployed when the vehicleis above a certain airspeed and/or certain altitude. In one aspect,being above the threshold airspeed and/or altitude provides additionaltime and distance to allow proper sequencing of the drogue and mainparachutes. In another aspect, being above the threshold airspeed and/oraltitude may make it more challenging for the main parachutes (alone,without the drogue) to achieve sufficient stability and deceleration ofthe vehicle. Thus, above the certain airspeed and/or altitude, a drogueparachute is deployed first. A flight computer may determine whether thevehicle is in a suitable state (e.g., based on altitude, airspeed,and/or other vehicle state information) for deploying the drogue or ifinstead the main canop(y/ies) are to be deployed without first deployingthe drogue. In some embodiments, vehicles operate above a certainairspeed only above a specified altitude. For example, the flightprofile of a vehicle may require the vehicle to operate above a certainairspeed only above a specified altitude. In some embodiments, when avehicle is traveling at above 25 mph and on the order of hundreds offeet (e.g., 100-300 feet), then a drogue is deployed first.

In an embodiment, a drogue is deployed, the vehicle slows (e.g., after awaiting period), and then one or more main canop(y/ies) are deployed.Referring to FIG. 9A, drogue 902 a is deployed. The drogue may beattached to the vehicle 900 at the same attachment point as the maincanopies (see FIG. 7A for an example of where the main canopies areattached). The drogue 902 b in FIG. 9B is fully deployed and the canopyopened, bringing the vehicle to a stable state suitable for the maincanop(y/ies) to be deployed. In some embodiments, sensors may reportback to a flight computer the vehicle's airspeed and when the speedmeets/is below a threshold, then the flight computer triggers thedeployment of one or more main canop(y/ies) as shown in FIG. 9C. In thisexample, all three main canopies 920 (corresponding to 702) are deployedat once and deployment proceeds according to FIGS. 7A and 7B or FIGS. 8Aand 8B. In other embodiments, canopies may be deployed one (or a few) ata time. The drogue may be extracted using a rocket, mortar, pilotparachute, pressurized device, or other means of extraction. The droguemay be cut away from the vehicle prior to extraction of the mainparachutes as shown. Alternatively, the drogue may remain connected tothe vehicle. In some embodiments, a drogue parachute has a smallersurface area compared with a main parachute and permits more air to movethrough the canopy.

In some embodiments, canopy extraction may occur in sequence or in quicksuccession in order to reduce peak loading on the pilot due to canopiesopening simultaneously at high speeds, but also occurring fast enough toensure all canopies are fully extracted before any one is fully inflatedin order to avoid striking canopy fabric with a rocket deployed later insequence.

The following figures describe example canopies and lines which may beused to implement a (e.g., single) parachute canister such as 600 a-600c in FIG. 6. First, canopies and lines will be described (FIGS. 10-21),then a canister will be described (FIGS. 26 and 27). The parachutesdescribed below are merely exemplary and are not intended to belimiting. For example, other parachutes (e.g., comprising some othercanopies and lines with some other arrangements and/or features) whichcan quickly inflate (e.g., for use at relatively low altitudes) may alsobe used.

A parachute tow and release system with canopy extraction controlled bya drag surface is disclosed. The techniques described here includeparametrically tuning extension damping and air inflow to reduce recoiland decrease parachute inflation time. In some embodiments, a parachutedeployment system includes a parachute coupled to a release via a firstload path. The first load path includes parachute lines attached to acrown of the parachute. These parachute lines are called upper parachutelines or crown lines. The system includes a release adapted to attachthe parachute to a rocket via the upper parachute lines, and disengagethe parachute from the rocket if a load shifts from the first load pathto a second load path. The system includes a line constrainer providedbetween the release and the parachute. The upper parachute lines passthrough the line constrainer, and the line constrainer is adapted torestrict an extent to which the upper parachute lines are able to extendaway from a longitudinal axis of the parachute.

In various embodiments, the first load path further includes one or morelower parachute lines (also called suspension lines). The systemincludes a lower parachute line restrainer which, when released, permitsthe lower parachute line(s) to extend to full length. The full extensionof the lower parachute line(s) causes the load to shift from the firstload path to the second load path. The second load path includes arelease line that becomes taut when the load shifts. Consequently, theparachute is disengaged from the rocket via the release, the releaseline and upper parachute lines separate from the release, and the rocketassembly propels itself away from the main parachute assembly. In someembodiments, the upper parachute lines function as tow lines. That is,the same set of lines are both upper parachute lines and tow lines. Anexample of a parachute deployment system in which the upper parachutelines and tow lines are the same is shown in FIGS. 19A and 19B. Thesecond load path, in various embodiments, includes a release line.

First, some embodiments of a parachute system without a line constrainer(e.g., on or around the upper parachute lines) are described. Thisenables a simpler and/or clearer explanation of how the load shiftingfrom a first load path to a second load path enables a rocket to bereleased or otherwise decoupled from the parachute (e.g., without theadded complexity of having to discuss a line constrainer). Then, someembodiments of a parachute system with a line constrainer on the upperparachute lines are described. This enables the discussion of thoselater embodiments to focus more clearly and/or easily on those lineconstrainer embodiments and how they further improve the parachutesystem.

Quickly extracting the parachute using a rocket exerts a high load on atleast one line (e.g., the rocket tow line and also the upper parachutelines or crown lines) connecting the rocket and the parachute. Therocket is released or otherwise disconnected from the parachutefollowing parachute extraction for various reasons. For example, if therocket remains attached, it may present a fire hazard to the parachute,add undesirable weight to the parachute and payload, and/or cause theparachute to move in an undesirable and/or unpredictable manner. Theadditional line length may constrict the fabric of the canopy and mayprevent the parachute from opening freely. The manner in which therocket is released or otherwise disconnected from the parachute must becarefully considered. For example, severing (e.g., directly cutting) theline that connects the rocket and the parachute while the line is underhigh load (e.g., because the rocket is pulling the line taut) causes theline and/or parachute to recoil. Recoil of the parachute may result inunpredictable inflation, line tangling, and/or altitude loss, and istherefore undesirable.

The amount of recoil can be tuned according to the techniques describedhere. Recoil can be controlled by adjusting, for example, the amount ofdamping or drag induced by a surface moving through the air as theparachute is extracted or extended. A high level of damping correspondsto less recoil. A low level of damping corresponds to more recoil. Asmore fully described below, extension damping is tuned by controllingthe extent to which upper parachute lines are permitted to extend awayfrom a longitudinal axis of the parachute. Tunable extension dampingfinds application in a variety of flying conditions. For example, whenan aircraft is intended to fly relatively close to the ground, recoil isundesirable because the more recoil there is, the more likely that theaircraft will lose altitude and hit the ground. Thus, for low-flyingaircraft, the extension damping of the parachute can be tuned to have ahigh level of damping. Conversely, for relatively high flying aircraft,there is greater tolerance for altitude loss/recoil, and the extensiondamping can be tuned to have a relatively low level of damping.

In some embodiments, a parachute deployment system comprises a tow line,a set of upper parachute lines (crown lines), a (e.g., separate) releaseline, and a line constrainer. The line constrainer is adapted torestrict an extent to which the upper parachute lines are able to extendaway from a longitudinal axis of the parachute. In some embodiments,restricting the extension of the upper parachute lines allows extensiondamping to be tuned to reduce recoil. In some embodiments, both the towand release lines are attached to a release which connects the rocketand the parachute and (e.g., at the appropriate time or condition)disconnects the rocket and the parachute from each other. In someembodiments, having a separate tow line and release line allows theparachute to be extracted quickly (e.g., using the tow line where thetow line is taut and the release line is slack) and the rocket to bereleased smoothly (e.g., when the release line becomes taut). In thedisclosed system, the tow line first takes the load of the payload. Thatis to say, the tow line is part of a load path that connects the rocketto the payload. The load path may comprise the tow line, upper lines ofthe parachute or crown lines, suspension lines of the parachute, and ariser of the parachute. In some embodiments, various parts of theparachute (e.g., the lines, the riser, etc.) are constructed of nylonbecause nylon is better for shock absorption. In some embodiments, therelease line is situated (e.g., runs) parallel to the tow line but isslack and bears no load (at least initially). A lower parachute linerestrainer (at least in some embodiments) is configured to release undera threshold force and may release after a canopy of the parachute isfully extracted. In some embodiments, release of the lower parachuteline restrainer causes the load to shift from the tow line to therelease line. For example, the release line begins to be pulled taut. Insome embodiments, the load is shifted by changing relative lengths ofthe lines. Due to the load on the release line, the release opens. Insome embodiments, the release opens under a small load. The opening ofthe release causes the rocket and the parachute to detach.

FIG. 10 is a diagram illustrating an embodiment of a parachutedeployment system. In the example shown, rocket 1000 is tethered torelease 1004. In some embodiments, rocket 1000 is permanently attachedor connected to release 1004. For example, release 1004 is designed toremain with rocket 1000 following separation of rocket 1000 and canopy1010. In various embodiments, release 1004 comprises a latch, a cutter,a pin, or any other appropriate release. As will be described in moredetail below, the release is designed to disconnect the rocket from therest of the aircraft (including the parachute) with minimal recoil.

Tow line 1008 is attached to release 1004 at its upper end. At its lowerend, tow line 1008 is attached to canopy 1010 via the upper parachutelines. Upper parachute lines are attached to the canopy in the middle ofthe canopy, between an apex and outer edge of the canopy. In someembodiments, attaching the upper parachute lines to the middle of thecanopy or lower on the canopy than its apex allows lower sections of thecanopy to be pulled out quickly, which helps when the aircraft is at alow altitude, and provides even distribution of tension across all lowerparachute lines. In various embodiments, tow line 1008 is attached tocanopy 1010 using 4, 70, 20, or any appropriate number of upperparachute lines. The upper parachute lines are positioned equidistantaround the canopy. In some embodiments, the canopy is packed andinitially extracted in an “M” cross-sectional shape which inflates morequickly than a typical cylindrical shape. For example, the apex of thecanopy is packed in an inverted position.

Suspension lines 1012 extend from canopy 1010. In various embodiments,various numbers of suspension lines are used. A portion of thesuspension lines is folded up and held in lower parachute linerestrainer 1016. In various embodiments, lower parachute line restrainer1016 comprises a bight, a tied or sewed cloth, a thin plastic tube, acardboard loop, or any appropriate restrainer that holds the suspensionlines such that their lengths are effectively shortened. The lowerparachute line restrainer is configured to release under a thresholdforce (e.g., due to the rocket). For example, the lower parachute linerestrainer is configured to break, rip, tear, or open under thethreshold force. The suspension lines 1012 and release line 1014 areattached at their bottom ends to riser 1017. In various embodiments,riser 1017 comprises one line, multiple lines, or webbing. Riser 1017 isattached to payload 1018. In some embodiments, payload 1018 comprises anaircraft.

In some embodiments, the release line is tied directly from the releaseto the bottom of the suspension lines. In some embodiments, the releaseline is tied to the apex, which in turn is tied to the center line. Thecenter line extends from an apex of the canopy to a confluence point atthe bottom of the suspension lines. In some embodiments, the releaseline is tied directly to the center line.

The following figures show examples of the exemplary parachutedeployment system at various points in time in order to betterillustrate how the parachute deployment system works and how it is ableto disconnect the rocket with little or no recoil.

FIG. 11A is a diagram illustrating an embodiment of a parachutedeployment system in a stowed state. In the example shown, a parachuteis stowed inside can 1105A. Canopy 1102A is folded and stored in the canalong with release 1100A. The can is stored on or in payload 1106A,which may comprise a cavity or compartment in an aircraft where theparachute deployment system is stored. Rocket 1104A is positionedexternally to the can.

FIG. 11B is a diagram illustrating an embodiment of a parachutedeployment system following rocket deployment. Upon triggering theparachute deployment system, rocket 1104B begins traveling upwards awayfrom payload 1106B. The rocket is attached to and tows release 1100B.Release 1100B in turn is attached to the parachute via tow line 1108Band release line 1110B. Canopy 1102B remains folded inside of can 1105B.It is noted that in the state shown here, the tow line 1108B is taut andthe release line 1110B is slack.

FIG. 11C is a diagram illustrating an embodiment of a parachutedeployment system wherein the parachute is towed via a tow line. In theexample shown, canopy 1102C has been extracted and is no longer in thecan (not shown). Rocket 1104C tows release 1100C. Release 1100C isattached to canopy 1102C via tow line 1108C and upper parachute lines1109C which are sometimes referred to as crown lines. Suspension lines1112C extend from canopy 1102C and a portion of the lines is held inlower parachute line restrainer 1114C, shortening the effective lengthsof the lines. Release line 1110C extends from release 1100C. Suspensionlines 1112C and release line 1110C are attached to riser 1116C.

As shown, rocket 1104C is towing canopy 1102C upwards via tow line 1108Cand therefore tow line 1108C is taut. Release line 1110C is slack in thestate shown. In some embodiments, the length of release line 1110C islonger than the combined length of the tow line, canopy length betweenthe tow line and suspension lines, and suspension lines held in lowerparachute line restrainer 1114C. In this initial extraction state,neither the tow line nor the release line are under load. As the rockettravels further from the payload, the combined length of tow line 1108C,suspension lines 1112C, and riser 1116C are pulled taut. Once thatoccurs, the portion of the canopy between the tow line and suspensionlines is also pulled taut. At this point, the parachute is fullyextracted from the can. The rocket pulls upwards on the combined lengthwhile the payload exerts a downwards force on the combined length due toinertia. The tow line is under load, whereas the release line remainsslack and is not under load. The load path from the rocket to thepayload travels through the tow line, suspension lines held in therestrainer, and riser rather than traveling through the release line andriser because the release line is longer in length than the combinedlength of the tow line, suspension lines held in the restrainer, andintermediaries such as the portion of the canopy between the tow lineand suspension lines or lines used to attach the tow line to the canopy.

FIG. 11D is a diagram illustrating an embodiment of a parachutedeployment system during release of a lower parachute line, canopy line,and/or suspension line restrainer. For simplicity, a lower parachuteline restrainer is described in this example, but in other embodiments arestrainer is associated with a canopy line and/or suspension line(e.g., in addition to or as an alternative to a lower parachute line).In this example, the lower parachute line restrainer is configured torelease under a first threshold force. In some embodiments, the lowerparachute line restrainer is configured to release after the parachuteis fully extracted from the can. For example, the first threshold forceis equal to a force the lower parachute restrainer experiences in theevent the suspension lines are pulled taut. In some embodiments, thefirst threshold force is equal to a force that the lower parachute linerestrainer experiences in the event of sustained load on the suspensionlines. For example, the lower parachute line restrainer will not breakimmediately in the event the suspension lines are pulled taut, but ashort time after due to the forces exerted by the rocket and payload. Insome embodiments, the first threshold force is determined based onexperimental data. The type of lower parachute line restrainer may bechosen based on the first threshold force. The lower parachute linerestrainer may be calibrated based on the first threshold force. Forclarity, suspension lines 1112D and lower parachute line restrainerpieces 1118 and 1120 are shown pulled to the side so that they are notobscured by release line 1110D. In actuality, the suspension lines 1112Dmay be pulled straight (e.g., between the rocket and payload) when thelower parachute line restrainer breaks or otherwise releases.

In the example shown, lower parachute line restrainer pieces 1118 and1120 have broken off of suspension lines 12D. The suspension lines asshown have been released from their taut, shortened position. Tow line1108D is taut. Release line 1110D is slack. As rocket 1104D continuestraveling upwards away from payload 1106D, both tow and release linesmay first be slack because both are too long to restrain the rocketinitially. As the rocket continues traveling or the payload continuesfalling, load will eventually transition to release line 1110D due toits shorter length compared to the longer combined length of the towline, canopy portion, and suspension lines (no longer shortened by thelower parachute line restrainer).

FIG. 11E is a diagram illustrating an embodiment of a parachutedeployment system wherein the tow load imparted by the rocket istransferred to a release line. It is noted that the parachute isn'tactually towed at this point. In the example shown, suspension lines1112E are at their full, unrestrained length. The suspension lines 1112Eare slack because the load has shifted to release line 1110E such thatrelease line 1110E is taut. The load path from rocket 1104E to payload1106E now comprises release line 1110E and riser 1116E. In someembodiments, the release line is attached to the center line and then tothe riser. The release line is shorter in length than the combinedlength of the length of tow line 1108E, the upper parachute or crownlines (1109E), the length of the portion of canopy 1102E that is inbetween the tow line and the suspension lines, and the length of onesuspension line.

The release line is configured to open release 1100E under a secondthreshold force. Some examples of the release are described in moredetail below. In some embodiments, the second threshold force is a lowforce. The second threshold force may be lower than the first thresholdforce required to release the lower parachute line restrainer. A desiredlevel of force for the second threshold force may be determinedexperimentally. In the event the release line is under the secondthreshold force, release 1100E opens. In some embodiments, the openingof release 1100E allows the parachute and rocket to separate with littleor no recoil.

FIG. 11F is a diagram illustrating an embodiment of a parachutedeployment system wherein the parachute is separated from a rocket. Inthe example shown, rocket 1104F remains tethered to release 1100F. Therocket and release are separated from the parachute and payload. Releaseline 1110F and tow line 1108F and upper parachute lines 1109F danglefrom canopy 1102F. In some embodiments, canopy 1102F completely fillsfollowing detachment of the rocket.

In some embodiments, a parachute deployment system includes othercomponents and/or is configured in some other manner not shown here. Thefollowing figure describes one such alternate.

FIG. 12 is a diagram illustrating an embodiment of a parachutedeployment system. In this example, the rocket 1200 has an attachedparachute 1202 that allows the rocket to float to the ground. Theparachute may be installed for safety to prevent the rocket fromimpacting a person or object at a high speed and causing damage.

In various embodiments, the parachute is towed from different points onits canopy and this figure shows an example different from that shown inthe previous figures. In this example, tow line 1210 is attached at theapex of canopy 1212. Canopy 1212 is extracted in a roughly triangularcross-section shape.

In various embodiments, the lower end of the release line is attached atdifferent points. For example, the release line as shown is attached tothe payload directly. In some embodiments, the release line is attachedto a riser of the parachute.

In some embodiments, the lower parachute line restrainer restrains ariser of the parachute rather than suspension lines. In the exampleshown, lower parachute line restrainer 1218 holds a riser of theparachute in a position such that its effective length is shortened. Forexample, loops of the riser are folded back and forth and secured.Release line 1216 is longer than a combined length of the length of towline 1210, a length from apex to opening of canopy 1212, a length of onesuspension line of suspension lines 1214, and the riser as restrained bylower parachute line restrainer 1218. In the event lower parachute linerestrainer 1218 is released, the release line is shorter than the priordescribed combined length.

In some embodiments, the relative lengths concept remains the sameregardless of positioning of the release line, tow line, and lowerparachute line restrainer. For example, a first load path which includesthe tow line is initially longer than a second load path which includesthe release line. Following release of the lower parachute linerestrainer, the first load path is shorter than the second load path,which eventually causes the load path to change.

In some embodiments, the parachute deployment system includes a ripstitch (not shown here). A rip stitch is a fabric piece that is designedto rip in order to absorb shock when the parachute deploys, reducingline loading and thus reducing recoil. In some embodiments, a rip stitchis placed at the very bottom of the riser and/or at the bottom of thesuspension lines.

The following figure describes the examples above more generally and/orformally in a flowchart.

FIG. 13 is a flow diagram illustrating an embodiment of a process todeploy a parachute, including release of a rocket. At 1300, a parachuteis towed by a rocket via a tow line. For example, the rocket beginstraveling upwards and away from the payload. As the rocket travelsupwards, a release is first pulled out from being stowed (e.g., therocket is attached to the release), followed by a canopy of theparachute, followed by suspension lines of the parachute. Eithersuspension lines or a riser of the parachute is held in a lowerparachute line restrainer. See, for example FIG. 11C.

At 1302, it is determined whether to release a lower parachute linerestrainer. For example, a lower parachute line restrainer may bedesigned to release if the lower parachute line restrainer is subjectedto a force greater than a first threshold force. In the event the lowerparachute line restrainer is not subjected to a force greater than thefirst threshold force, the parachute continues to be towed by the rocketvia the tow line. For example, the rocket continues pulling upwards onthe tow line. The payload continues exerting a downwards force on thetow line. See, for example, FIG. 11C.

In the event it is determined to release the lower parachute linerestrainer, at 1304 the lower parachute line restrainer releases,causing the one or more lower parachute lines to release to their fulllengths. In some embodiments, the lower parachute line restrainereffectively shortens the lengths of the one or more lower parachutelines and they are restored to their full length following the releaseof the lower parachute line restrainer. See, for example FIG. 11C wherethe lower parachute lines are folded and tied using the lower parachuteline restrainer, which reduces their effective length. The release ofthe lower parachute line restrainer may comprise breakage, snapping,fraying, or any other release. The change in relative lengths causes thetow line to become slack (e.g., because its effective length increases).In some embodiments, the release line eventually becomes taut (e.g.,because the increase in the effective lengths of the lower parachutelines causes the load path which includes the release line to be shorterthan the load path which includes the now-released lower parachutelines).

At 1306, it is determined whether a load switches from a first load pathwhich includes the tow line and the lower parachute lines to a secondload path which includes a release line. For example, because the lowerparachute lines are now released, that load path now has a longereffective length than the load path which includes the release line.Eventually, the load path which includes the release line will be pulledtaut, switching the load onto that line. See, for example, FIG. 11E.

In the event the load switches from the first load path which includesthe tow line and the lower parachute lines to the second load path whichincludes the release line, at 1308 the release opens, permitting therocket and the parachute to separate. In some embodiments, the releaseline is configured to open the release if a second threshold force isexceeded (e.g., the tow line and release line are configured to separatefrom the release in the event the release line experiences a forcegreater than the second threshold force). For example, one or both ofthe lines may be released from a latch or cut using a cutter. Moredetailed examples of the release are described below. If the load doesnot switch from the first load path to the second load path, the processmay continue to check whether this condition is satisfied.

In some embodiments, the release remains with the rocket. The tow lineand the release line separate from the release, allowing the parachuteto be separated from the rocket and released. See, for example, FIG.11F.

The following figure provides some context for the process of FIG. 13(e.g., with respect to which line is bearing the load at various stepsin FIG. 13).

FIG. 14 is a flow diagram illustrating an embodiment of a parachutedeployment process with load-bearing context. In this example, contextfor various steps in FIG. 13 is provided, primarily with regard to whichline is bearing the load at various steps. In some embodiments, both thetow line and the release line are under no load at the beginning ofparachute extraction (e.g., before the rocket is ignited). Both linesare slack as the rocket begins to propel away from the payload. Two loadpaths are available that connect the rocket and the payload. A firstload path including the tow line is (initially) shorter than a secondload path including the release line (e.g., because one or more lowerparachute lines are wound up and tied, effectively shortening them). Asthe distance between the rocket and the payload reaches the length ofthe first load path, line elements in the first load path become tautand are under load. The second load path is not loaded and line elementsin the second path are slack. At 1400, the tow line is under load andthere is no load on the release line. In the context of FIG. 13, step1400 may describe step 1300.

At 1402, the lower parachute line restrainer releases, causing load totransfer to the release line. This step relates to steps 1304 and 1306in FIG. 13. Release of the lower parachute line (see step 1304 in FIG.13) causes the first load path to be longer than the second load path byextending the (e.g., effective) length of a line element of the firstload path (e.g., a riser or suspension lines). In some embodiments, bothload paths are momentarily not loaded upon the extension of length ofthe first load path. As the distance between the rocket and the payloadreaches that of the second load path, either due to the payload droppingor the rocket propelling upwards, line elements in the second load pathsuch as the release line are pulled taut. See, e.g., step 1306 in FIG.13. In some embodiments, the second load path experiences only a smallload before triggering the release to open. The full line load of thetow line may not be transferred to the release line.

At 1404, the load on the release line causes the release to open. Seestep 1308 in FIG. 13. In some embodiments, the lower parachute linerestrainer is configured to release when the parachute is fullyextracted. In quick succession, the release is subsequently opened whichallows separation of the rocket and parachute. The tow line experiencesa large load (e.g., which is good for deploying the parachute quicklyand at high speed and/or low altitudes) whereas the release lineexperiences a small load (e.g., which is good for little or no recoil)before quickly triggering release. Once the parachute is fullyextracted, the rocket is no longer needed.

At 1406, the rocket and the parachute are separated. The rocket issafely removed without causing a rebound or reactionary movement fromthe parachute.

As described above, a release may comprise a variety of components. Thefollowing figures describe some examples where the release includes alatch and a cutter. For clarity, the exemplary release is described atvarious points at time.

FIG. 15A is a diagram illustrating an embodiment of a release comprisinga latch and a cutter. In some embodiments, release 1004 of FIG. 10 isimplemented as shown here. In this example, the load on the release linecauses a cutter to be pulled downwards. The cutter is pulled down on aline, binding, or wrapper that holds a latch shut, causing the latch toopen. A tow line held in the latch is released.

In the example shown, cutter 1500A and latch 1510A are positionedadjacent to each other. Latch 1510A as shown comprises a rectangularcomponent and a curved component. Generally speaking, the latch isU-shaped with a hinge so that the curved part can swing away from therectangular part. In this example, the curved part is shaped to providea mechanical advantage such that the high tow line load can be reactedby a lower latch restrainer load on 1504A. This allows the latchrestrainer to be smaller, which makes it easier to cut (e.g., it lowersthe cut and/or release load).

Latch restrainer 1504A as shown holds latch 1510A in a closed position(e.g., with all parts of the latch forming a continuous loop without anopening or break). For example, the latch restrainer clamps two top endsof the latch together so that the latch cannot open. Latch restrainer1504A may comprise a line or a strip of fabric. In this example, latchrestrainer 1504A is made of a material that is able to be cut with ablade, such as cotton or nylon.

In the example shown, latch restrainer 1504A loops through cutter 1500A.In some embodiments, latch restrainer 1504A is exposed to a blade of thecutter through some other configuration or relative positioning of theblade and latch restrainer. For example, a blade is able to access andcut through the latch restrainer based on relative positions of thecutter and latch. In some embodiments, the latch restrainer is threadedthrough holes in the latch and/or cutter. For example, the latchrestrainer comprises a line that is threaded through a hole at the endof the rectangular component of the latch, a hole in an end of thecurved component of the latch, and through a hole in the side of thecutter.

In the example shown, release system restrainer 1506A is positionedaround cutter 1500A and latch 1510A. In various embodiments, the releasesystem restrainer comprises a zip tie, a line, a strip of fabric, or anyappropriate restrainer which tears or releases when sufficient force orload is exerted downward on release line 1508A and/or upward on line1502A to the rocket. In some embodiments, the release system restrainermaintains the positions of the cutter and the latch relative to eachother. For example, latch restrainer 1504A does not securely hold thepositioning of the cutter and the latch by itself. The release systemrestrainer holds the cutter in a position where the blade of the cutteris not in contact with the latch restrainer. In some embodiments, therelease system restrainer is configured to break or release under aspecific threshold force. In the event the specific threshold force isexerted on the release system restrainer, cutter 1500A will movedownward (e.g., due to tension in the release line) and cut latchrestrainer 1504A, causing latch 1510A to open. For example, the releasesystem restrainer breaks in the event the release line is under thesecond threshold force.

Tether 1502A is attached to the top of the latch 1510A as shown andattaches the latch to a rocket. Tow line 1512A is held inside of latch1510A (e.g., tow line 1512A is threaded through or around latch 1510A).In some embodiments, tow line 1512A implements tow line 1008 of FIG. 10.As shown, the tow line has a loop at its end and the curved component ofthe latch is positioned in the loop. The tow line is not permanentlyattached to the latch. Release line 1508A extends from the bottom ofcutter 1500A. In some embodiments, release line 1508A implements releaseline 1014 of FIG. 10.

FIG. 15B is a diagram illustrating an embodiment of a release wherein arelease system restrainer is broken. In the event release line 1508B isunder load, a force is exerted on the release system restrainer. In theevent the force exerted on the release system restrainer exceeds thespecific threshold force of the release system restrainer, the releasesystem restrainer breaks or releases. In the example shown, releasesystem restrainer pieces 1514 and 1516 have broken off. Cutter 1500B andlatch 1510B are shown in their positions immediately as the releasesystem restrainer is breaking off. In the example shown, latchrestrainer 1504B remains intact.

FIG. 15C is a diagram illustrating an embodiment of a release wherein alatch restrainer is broken. In some embodiments, without the releasesystem restrainer intact, the cutter falls downwards relative to thelatch. For example, the cutter falls because it is being pulled byrelease line 1508C and the latch is towed upwards by the rocket via line1502C. In the example shown, cutter 1500C drops in its position relativeto latch 1510C, severing latch restrainer 1504C. Following the severanceof latch restrainer 1504C, cutter 1500C remains attached to theparachute via release line 1508C but is no longer attached to latch1510C or the rocket. Latch 1510C remains tethered to the rocket via line1502C. At the moment shown, latch 1510C is in a closed position.

FIG. 15D is a diagram illustrating an embodiment of a release wherein alatch is open. After the latch restrainer is cut, the latch opens (e.g.,the curved part of the latch has rotated about a hinge, causing it toseparate from the rectangular part of the latch). Latch 1510D is shownin an open position. Tow line 1512D as shown remains on the curvedcomponent of latch 1510D. As the rocket tows latch 1510D up and away,tow line 1512D slips off of latch 1510D. In some embodiments, a smalladditional load on tow line 1512D causes the tow line to come off oflatch 1510D. For example, as the rocket continues flying and the payloadcontinues dropping, tow line 1512D is pulled taut and pulled off fromlatch 1510D. In various embodiments, the two halves of the latch mayseparate to various degrees (e.g., nearly 180° if desired) by adjustingor configuring the hinge as desired. In some embodiments, the two halvesof the latch may separate completely after the latch opens.

Because the tow line 1512D slips off of open latch 1510D, there is verylittle recoil when the rocket separates from the parachute. In contrast,if a load path (e.g., bearing all of the load) were directly cut orotherwise severed, there would be a significant amount of recoil becauseof the tension or load on the line prior to the line being cut. Asdescribed above, a large amount of recoil is undesirable in someaircraft applications, which makes the techniques described hereinuseful.

FIG. 15E is a diagram illustrating an embodiment of a parachutedeployment system following separation of the parachute and a rocket.The example shown provides an overall view of the parachute deploymentsystem following opening of the release. In the example shown, rocket1518 is attached to latch 1510E. After separating, the rocket may towthe latch for a distance and then begin to drop. In some embodiments,the rocket has its own recovery system (e.g., a parachute).

Release line 1508E and attached cutter remain attached to parachute1520. Tow line 1512E (and upper parachute lines and/or crown lines) alsoremains attached to parachute 1520. As shown, parachute 1520 iscompletely filled and is attached to payload 1522.

FIG. 16 is a diagram illustrating an embodiment of a cutter with achannel to thread the latch restrainer through. In various embodiments,the cutter is configured in different ways. In this example, vibrationsthrough lines, movement of the rocket/payload, or environmental factorssuch as wind may cause the blade of a cutter to come into contact withthe latch restrainer earlier than desired (e.g., when the release lineis not under load). To address this, the exemplary cutter shown here isconfigured to minimize chances of accidental severance of the latchrestrainer (e.g., caused by vibrations, slipping, etc.).

In the example shown, cutter 1600 comprises a blade that is held in arecessed area within a frame. For example, blade 1602 is secured suchthat it cannot rattle or move (e.g., prematurely) from its position inthe cutter. Latch restrainer 1606 is threaded through a small channel orwindow in the cutter. Channel 1604 is a slim opening through the cutterthat allows blade 1602 to be pulled down on the latch restrainer and cutthe latch restrainer. Using a secured blade and a small channel ofaccess (e.g., through which the latch restrainer is threaded) decreasesthe chances of unintentional and/or premature cutting of the latchrestrainer.

FIG. 17 is a flow diagram illustrating an embodiment of a process toopen a release. In some embodiments, the process is used at step 1308 inFIG. 13. At 1700, the release system restrainer breaks. For example, therelease system restrainer breaks after a threshold force is exerted onthe release line. The release line may be under load following therelease of the lower parachute line restrainer, which changes the loadpath from one including the tow line to one including the release line.

At 1702, the cutter is pulled down on the latch restrainer via therelease line. For example, the latch restrainer and cutter move relativeto each other, causing the blade of the cutter to cut the latchrestrainer.

At 1704, the latch restrainer breaks. For example, the latch restrainermay be a line or tie that is cut. In some embodiments, the latch opensin the event the latch restrainer breaks. For example, in the previousfigures, the latch has a hinge and part of the latch falls open byrotating on the hinge.

As described above, a release may comprise a variety of components. Thefollowing figures describe some examples of a release having a soft pin.

FIG. 18A is a diagram illustrating an embodiment of a soft pin releaseassembly. Soft pin release assembly 1840 is adapted to disengage arocket from a parachute/payload. Soft pin release assembly 1840 is anexample of how release 1004 of FIG. 10 can be implemented. FIG. 18Bshows another view of an embodiment of a soft pin release assembly.

The soft pin release assembly includes release back plate 1844, soft pin1854, first line 1842, second line 1846, guide loop 1856, and break ties1848. The soft pin release assembly is passively actuated when a load onrelease line 1814 reaches a threshold force (also called a releaseforce). The soft pin release assembly exploits the rocket momentum andthrust when a parachute reaches a fully extracted state, actuating inresponse to the release force exerted by the rocket momentum and thrust.

In the example of FIGS. 18A and 18B, the release assembly is in anunactuated state. Release back plate 1844 is structured to accommodatesoft pin 1854. The release back plate can be made of an inflexiblematerial such as metal, plastic, and the like. The release back platecan be made of a flexible material such as nylon, webbing, and the like.Here, soft pin 1854 is held in place against release back plate 1844 bya loop of the second line 1846 (that passes around a portion of the softpin 1854 and through an opening of the release back plate), guide loop1856, and break ties 1848.

Soft pin 1854 is adapted to minimize mass and inertial loading underacceleration, for example around 500-1000 g acceleration. Soft pin 1854may be made of a flexible material such as cloth, rope, plastic, and thelike in order to achieve this property or performance. Unlikeconventional metal pins, a soft pin is able to avoid backing itself outof the release back plate. Referring to FIG. 18B, pin pigtails 1852prevent the soft pin from backing itself out even when there is highinertial loading (e.g., load directed to the left of the soft pin). Insome embodiments, soft pin 1854 is arranged such that approximately halfof the pin mass is on each side of guide loop 1856 to prevent the pinfrom sliding in or out under inertial loads.

Guide loop 1856 reacts to inertial loading of the soft pin (e.g., at500-1000 g) as the assembly is accelerated, and does not break. Guideloop 1856 is adapted to guide the motion of the soft pin duringactuation of the release as more fully described below. In someembodiments, the guide loop is made of a hard material or a ring.

Break ties 1848 are adapted to retain the soft pin against the releaseback plate below the release force, and break in response to loading ofthe release line (e.g., at the release force). When a release force ismet or exceeded, release line 1814 tensions, causing the break ties 1848to break (not shown). Consequently, soft pin 1854 slips away from therelease back plate 1844, and crown lines 1808 are disengaged fromrelease back plate 1844 and the first line 1842. The rocket tow line1806 tows the rocket away from the parachute/payload. Break ties 1848can be adapted to respond to a desired release force by selecting amaterial with a desired strength or by positioning the break tie atvarious locations along the release back plate.

This release assembly is an example of a two-ring release that reducesthe force needed to release compared with other types of assemblies. Thetwo-ring release includes two line lengths in series (here, first line1842 and second line 1846). Here, the force required for the pin toreact to the rocket tow force is around a quarter of the rocket towforce. When (around) the force required to break ties 1848 and pull thepin is reached, the release is actuated. Break ties 1848 break, allowingsoft pin 1854 to slip away from release back plate 1844, freeing crownlines 1808 and the parachute/payload to disengage from the rocketassembly with minimal recoil (e.g., which means less falling or droppingof any attached aircraft or person before the parachute (re)inflates).

Also shown in FIGS. 18A and 18B are other components of a parachutedeployment system including crown lines 1808, rocket tow line 1806, andrelease line 1814. These components are like those described in theother figures unless otherwise described here. Referring to FIG. 19A,rocket tow line 1902 corresponds to rocket tow line 1806 of FIG. 18A.Returning to FIG. 18A, crown release lines 1808 are individually loopedthrough first line 1842 as shown. First line 1842 is looped throughsecond line 1846, which is then looped through soft pin 1854 to keep thesoft pin in place when the release is in an unactuated state as shown.In some embodiments, the crown lines are made of a low mass material todecrease and avoid interference with fast inflation after release.

Bridle 1842 is arranged to run from the rocket tow line to a rocketparachute. In a stowed state, the bridle is tucked inside the parachutecanopy such as canopy 1010 of FIG. 10. The bridle runs to a rocketparachute such as parachute 1202 shown in FIG. 12. The rocket parachutecanopy is tucked inside a main parachute canopy.

Rocket tow line 1806 runs from the release back plate to the rocket.When the release is actuated, the rocket tow line remains coupled to therocket, and pulls the release back plate away from the crown lines 1808to free the parachute/payload from the rocket assembly including theback plate with minimal recoil.

Release line 1814 runs between soft pin 1854 and a parachute centerlinethat runs from the parachute apex to the suspension line confluencepoint. When a rocket is deployed, the release line is extended as morefully described with respect to FIGS. 11A-11F. In response to tensioningof the release line, the release is actuated by the breaking of thebreak ties 1848. In various embodiments, the release line has ampleslack to avoid actuating the release prematurely.

In contrast to the release shown in FIGS. 15A-16, the release of FIGS.18A and 18B does not require a cutter, which may reduce the weight andincrease the reliability of the parachute deployment system. In variousembodiments, the soft pin release assembly is tolerant of packing underpressure in a can, which facilitates minimization of stowed parachutevolume and clean packaging. The soft pin release assembly, in variousembodiments, tolerates chaotic extraction and snatch from the can, anddoes not release prematurely due to rips, tears, or inertial loads. Forexample, the soft pin release assembly is agnostic to rotation. Onrelease, the soft pin release assembly avoids tangling and snags. In analternative embodiment, the release assembly is implemented by a snapshackle.

The following figures show examples of a parachute tow and releasesystem with canopy extraction controlled by drag surface, e.g.,controlled drag during parachute extraction. A parachute initiatesinflation prior to beginning its downward fall by allowing air to flowin through the parachute crown and spread the skirt for easier inflationonce the downward stroke begins. The period during which the parachuteis extracted and air flows in through the crown is called the extensionstroke, and the beginning of the falling is called the downward stroke.The release mechanism disclosed accommodates high extraction speeds inwhich the parachute is extracted at around 50-100 mph relative to theairstream. Typically, fast extraction of the parachute causes theparachute to slam against its full extension point, which in turn loadsthe lines of the parachute and causes recoil. Recoil causes a payload tolose altitude, which is undesirable because of potential payload damageor loss and less time or height for the parachute to slow down anyattached aircraft or person. The techniques described here allow controlof the extension of the parachute.

In one aspect, the extension stroke can be damped by controllingextension (e.g., in a radially outwards direction) of upper parachutelines. In some embodiments, extension damping is tunable by providing aline constrainer. Example line constrainers are shown in FIGS. 19A and19B. Because the type/level of damping can be selected or otherwisecontrolled to some degree, the parachute need not extend with a largeamount of momentum and slam against its extension point. Instead, theextension stroke is controlled and the parachute can be extended moreslowly towards its extension point. The level of extension is aparameter that can be set or selected.

The following figures show examples of an exemplary parachute deploymentsystem having a line constrainer. The line constrainer restrictsextension of upper parachute lines to provide a desired level ofextension damping.

FIG. 19A is a diagram illustrating an embodiment of a parachutedeployment system including a line constrainer associated with a firstarea, A1. In the example shown, the system includes rocket 1900, release1904, line constrainer 1920, and parachute 1910. Each of the systemcomponents functions like those of FIGS. 11A-11F unless otherwisedescribed here.

Rocket 1900 is adapted to extract the parachute from a container. Forexample, in an unactuated state, the parachute is stored in a cavity orcompartment in payload 1918. Prior to deployment, the parachute may befolded inside the cavity, as more fully described with respect to FIGS.24 and 25. To actuate the parachute, the rocket deploys and pulls theparachute from the container. The momentum of the rocket causes release1904 to actuate at desired conditions, separating the rocket from theparachute (as described above).

Release 1904 is adapted to disconnect rocket 1900 from parachute 1910with minimal recoil. The level of extension damping or drag duringparachute extraction can be adjusted by selecting certain parameters orcharacteristics of the line constrainer 1920 as will be described inmore detail below. When the load pulls on the release, the releasecauses the parachute to detach from the rocket. The conditions thatcause the release to disengage the parachute from the rocket is morefully described with respect to FIG. 21E. In various embodiments, therelease includes a latch, a cutter, a pin (e.g., a soft pin), or thelike. In the example shown, rocket 1900 is connected to release 1904 viarocket tow line 1902. In some embodiments, rocket 1900 is permanentlyattached or connected to release 1904. For example, release 1904 isdesigned to remain with rocket 1900 following separation of rocket 1900and parachute 1910. The release can disengage from the parachute in avariety of ways as described with respect to release 1004 of FIG. 10 andFIGS. 15A-18B.

Parachute 1910 is adapted to facilitate smooth flight of payload 1918.For example, the parachute is used to help a payload such as an aircraftgently land at a desired location. Parachute 1910 includes a canopy,upper parachute lines 1908, and lower parachute lines 1912 (also calledsuspension lines). In this example, the upper parachute lines alsofunction as tow lines, and the two terms are used interchangeably. Insome embodiments, the tow line is separate from the upper parachute linesuch as in the system of FIG. 10. Tow lines 1908 are adapted to tow theparachute, which is different from the rocket tow line 1902 adapted totow the rocket.

Tow line 1908 is attached to release 1904 at its upper end. At its lowerend, tow line 1908 is attached to a canopy of parachute 1910. Incontrast to the example of FIGS. 11A-11F, here the upper parachute lines1908 are directly attached to the release. When the parachute isreleased from release 1904, each of the upper parachute linesindividually detaches from the release. This decreases the mass upstreamof the parachute that could potentially interfere with the opening ofthe parachute.

In various embodiments, the upper parachute lines are attached to thecanopy in the middle of the canopy, between an apex and outer edge ofthe canopy. In some embodiments, attaching the tow line to the middle ofthe canopy or lower on the canopy than its apex allows lower sections ofthe canopy to be pulled out quickly, providing even distribution oftension across lower parachute lines. In some embodiments, the canopy isstored in the can in a manner that allows the canopy to inflate quicklyas described with respect to FIGS. 24 and 25. The ability to quicklyextract and inflate the parachute may be especially helpful at lowerflight altitudes (e.g., on the order of a few meters), where a delay inparachute inflation may cause a payload (e.g., an attached aircraft orperson) to be damaged or lost.

Suspension lines 1912 allow a payload to be suspended from theparachute. Here, the suspension lines 1912 and a release line (notshown) are attached at their bottom ends to riser 1917. Riser 1917attaches payload 1918 to parachute 1910 via lower parachute lines 1912.Payload 1918 may be any object benefitting from a parachute such as anaircraft, package, human, and the like. In some embodiments, the releaseline is tied to an apex of canopy 1910, which in turn is tied to thecenter line, which is tied to the riser.

In various embodiments, a portion of the suspension lines is held in alower parachute line restrainer (not shown) such that the length of thesuspension lines is shortened, as more fully described with respect toFIG. 21B. For example, the lower parachute line restrainer can beimplemented by a bight, a tied or sewed cloth, a thin plastic tube, acardboard loop, or the like. The lower parachute line restrainer isconfigured to release under a threshold force (e.g., due to the rocketpulling away from the parachute). For example, the lower parachute linerestrainer is configured to break, rip, tear, or open when subjected tothe threshold force.

The number of upper parachute lines, suspension lines, and riser linescan be selected based on the payload or flight conditions. For example,several upper parachute lines (2, 4, 10, 20, or more) can be positionedequidistantly on the canopy. More lines may attach components moresecurely to each other, but would be heavier than fewer lines. In someembodiments, riser 1917 is implemented by a webbing.

Line constrainer 1920 is adapted to restrict an extent to which theupper parachute lines are able to extend away (e.g., radially outward)from a longitudinal axis (dashed line A1) of the parachute. In variousembodiments, the amount of extension damping is directly proportional toan area defined by the extent of the upper parachute lines. In FIG. 19A,the cross-sectional area of the dashed horizontal line through lineconstrainer 1920 is A1.

FIG. 19B is a diagram illustrating an embodiment of a parachutedeployment system including a line constrainer associated with a secondarea, A2. The example system shown in FIG. 19B includes the samecomponents as the system of FIG. 19A unless otherwise described here.Line constrainer 1930 restricts an extent to which the upper parachutelines are able to extend away from a longitudinal axis of the parachuteto area A2. A2 is smaller than A1 because line constrainer 1930restricts movement of the upper parachute lines to a greater degreecompared with line constrainer 1920. In various embodiments, the dampingdrag force is proportional to the area corresponding to the extent towhich upper parachute lines are able to extend away from a longitudinalaxis of the parachute. Thus, the system in FIG. 19A has higher dampingcompared with the system in FIG. 19B.

There are many advantages to using the line constrainer to restrictmovement of the upper parachute lines to parametrically tune extensiondamping. In one aspect, extension damping is tunable. This allows asystem to be adapted for a variety of flight situations. For example, ifan aircraft (payload of the parachute and rocket system) is expected tofly at relatively low altitude, then the line constrainer can beadjusted or sized to constrain the upper parachute lines to movementwithin a larger area, which corresponds to high damping. Unlikeconventional means to constrain lower parachute lines, the lineconstrainers in the examples shown in FIGS. 19A and 19B constrain theupper parachute lines.

The sizing of a cutout in the line constrainer controls how much airpasses through a mid-channel of the parachute. The shape of the canopydue to airflow through the canopy helps the parachute to inflate morequickly. For example, the larger cross-sectional area A1 of FIG. 19Arelative to the cross-sectional area A2 of FIG. 19B means that theparachute of FIG. 19A will inflate more quickly when a similarly sizedcutout allows air to pass through the line constrainer into the canopyon extraction. The operation of the parachute deployment system is morefully described with respect to FIGS. 21A-21F.

The line constrainer can be implemented by various materials. Forexample, the line constrainer can be made of a flexible material withholes through which the upper parachute lines pass. The line constrainercan be made of a rigid material. The line constrainer can be a varietyof shapes such as a disk, polygon, or the like. In some embodiments, theline constrainer includes a cutout to promote airflow to facilitatequick parachute inflation. For example, the line constrainer can be aring or other shape with a cutout. The following figures show examplesof the line constrainer.

In some embodiments, one or more locking stows are used in place or inaddition to the line constrainer. FIG. 22A to FIG. 22E show an exampleof a system with locking stows.

FIG. 20A is a diagram illustrating an embodiment of a rectangular lineconstrainer. In FIG. 20A, the line constrainer is rectangular with arectangular cutout 2004. FIG. 20B is a diagram illustrating anembodiment of a circular line constrainer. In FIG. 20B, the lineconstrainer is circular with a circular cutout 2006.

The body of the line constrainer can be made of various materials. Insome embodiments, the line constrainer is made of a flexible materialsuch as nylon. For example, grommets in the line constrainer for linepass-through can be made of metal. In some embodiments, the lineconstrainer is made of an inflexible material such as metal or hardplastic with spaces for line pass-through. The cutout 2004 allows air toflow through the line constrainer. The cutout can be open, mesh, or thelike.

In the embodiments shown here, grommets are provided on the lineconstrainer to guide crown lines into place in a parachute deploymentsystem. For example, referring to FIG. 19A, a line constrainer such asthe ones shown in FIGS. 20A and 20B is provided between a release 1904and parachute 1910. Crown lines 1908 pass through the grommets of theline constrainer to (removably) couple the parachute to the release1904. Returning to FIGS. 20A and 20B, four grommets 2002 are providedalong the perimeter of the line constrainer. For example, the grommetsmay be provided near (e.g., within some threshold distance of) theperimeter. Although this example shows four grommets, any number ofgrommets (e.g., suitable for the number of crown lines in the parachutedeployment system) may be provided.

The sizing of the line constrainer affects the level of extensiondamping. In various embodiments, the outer diameter (or perimeter) isproportional to a level of damping (because in these examples at least,the grommets are positioned near the outer diameter of the lineconstrainers shown). As discussed with respect to FIGS. 19A and 19B, arelatively large area bounded by the line constrainer causes higherdamping than a smaller area. Thus, a line constrainer with a relativelylarger diameter (or perimeter) causes higher damping than a lineconstrainer with a smaller diameter (or perimeter).

The sizing of the (e.g., center) cutout of the line constrainer affectsthe amount of air inflow through the line constrainer to the canopycausing the canopy to inflate. In various embodiments, the cutout 2004is sized based on a desired level of air inflow. A relatively largercutout permits more air inflow than a smaller cutout. The desired airinflow may depend on the size of a parachute canopy. Typically a smallerparachute requires less air flow to inflate than a larger parachute. Thedesired air inflow may depend on a target speed of parachute inflation.More air inflow permits a parachute to be inflated more quickly.Referring to FIGS. 20A and 20B, cutout 2004 is smaller than cutout 2006.Thus, a canopy of the same size would inflate more quickly in a systemas shown in FIG. 20A as compared to a system that has the lineconstrainer shown in FIG. 20B. The shape of the cutout shown here ismerely exemplary and is not intended to be limiting. The cutout can besized to permit a desired volume of air inflow.

The following figures show examples of the exemplary parachutedeployment system at various points in time in order to betterillustrate how the parachute deployment system works and how it is ableto disconnect the rocket with tunable extension damping (e.g., little orno recoil).

FIG. 21A is a diagram illustrating an embodiment of a parachutedeployment system following rocket deployment. In this state ofdeployment, rocket 2100 begins traveling away from can 2118 (here,substantially up), causing release 2104 (which is coupled to the rocketvia rocket tow line 2102) to be pulled out from the can. The release isattached to the parachute via tow line 2108 and the release line (notshown). In this example, the crown lines are the same as the tow lines.Parachute 2110 remains stowed inside can 2118. In some embodiments, thecanopy of the parachute is stored in the can in the manner more fullydescribed with respect to FIGS. 24 and 25. The can is stored on or in apayload of the rocket. The can may comprise a cavity or compartment inan aircraft where the parachute deployment system is stored.

FIG. 21B is a diagram illustrating an embodiment of a parachutedeployment system while the parachute is towed via a tow line. In thisstate of deployment, the rocket continues traveling away from can 2118,causing parachute 2110 to be pulled out from the can. This state issometimes called the “initial extraction state.” As shown, the extent towhich the crown lines 2108 are able to extend away from a longitudinalaxis of the parachute is restricted by line constrainer 2120. The lowerparachute lines 2112 extend from the skirt of the parachute, and aportion of the lower parachute lines is held in lower parachuterestrainer 2116, shortening the effective lengths of the lines. Thelower parachute lines 2112 and release line 2114 are coupled to riser2117.

In this state, the tow line 2108 is taut and the release line 2114 isslack. In some embodiments, the length of release line 2114 is longerthan the combined length of the crown line 2108, canopy length betweenthe crown line and lower parachute lines, and lower parachute lines heldin lower parachute line restrainer 2116. In this initial extractionstate, neither the tow line nor the release line are under load exceptfor the load on the tow lines required to pull the canopy out of thecan.

As the rocket travels farther away from the payload, the combined lengthof tow line 2108, suspension lines 2112, and riser 2117 are pulled taut.In response, the portion of the canopy between the tow line and lowerparachute lines is also pulled taut. At this point, the parachute isfully extracted from the can. The rocket pulls upwards on the combinedlength while the payload exerts a downwards force on the combined lengthdue to inertia. The tow line is under load, whereas the release lineremains slack and is not under load. The load path from the rocket tothe payload travels through the tow line, suspension lines held in therestrainer, and riser rather than traveling through the release line andriser because the release line is longer in length than the combinedlength of the tow line, suspension lines held in the restrainer, andintermediaries such as the portion of the canopy between the tow lineand suspension lines or lines used to attach the tow line to the canopy.

FIG. 21C is a diagram illustrating an embodiment of a parachutedeployment system during release of a lower parachute line restrainer.In this example, the lower parachute line restrainer is configured torelease under a first threshold force. The lower line restrainer 2116breaks into pieces as shown to allow the lower parachute lines to extendto their full lengths. In some embodiments, the lower parachute linerestrainer is configured to release after the parachute is fullyextracted from the can. For example, the first threshold force is equalto a force the lower parachute restrainer experiences in the event thelower parachute lines are pulled taut. In some embodiments, the firstthreshold force is equal to a force that the lower parachute linerestrainer experiences in the event of sustained load on the suspensionlines. For example, the lower parachute line restrainer will not breakimmediately in the event the suspension lines are pulled taut, but ashort time after due to the forces exerted by the rocket and payload. Insome embodiments, the first threshold force is determined based onexperimental data.

The type of lower parachute line restrainer may be chosen based on thefirst threshold force. The lower parachute line restrainer may becalibrated based on the first threshold force. For clarity, lowerparachute lines 2112 and lower parachute line restrainer pieces areshown pulled to the side so that they are not obscured by the releaseline. In various embodiments, the lower parachute lines may be pulledstraight (e.g., between the rocket and payload) when the lower parachuteline restrainer breaks or otherwise releases.

In the example shown, lower parachute line restrainer pieces have brokenoff of lower parachute lines 2112. The suspension lines as shown havebeen released from their taut, shortened position. The tow line is taut,and the release line is slack. As the rocket continues traveling upwardsaway from the payload, both lines may both be slack because both are toolong to restrain the rocket initially. As the rocket continues travelingor the payload continues falling, load will eventually transition to therelease line due to its shorter length compared to the longer combinedlength of the tow line, canopy portion, and lower parachute lines (nolonger shortened by the lower parachute line restrainer). Forsimplicity, a lower parachute line restrainer is described in thisexample, but in other embodiments a restrainer is associated with acanopy line (e.g., in addition to or as an alternative to a lowerparachute line).

FIG. 21D is a diagram illustrating an embodiment of a parachutedeployment system following the shifting of a load from a first loadpath to a second load path. Here, the load shifts to release line 2114.In the example shown, the lower parachute lines are at their full,unrestrained length. The lower parachute lines are slack because theload has shifted to release line 2114 such that the release line istaut. The load path from the rocket to the payload now includes releaseline 2114 and the riser. As described above, in some embodiments, therelease line is attached directly from the release to the bottom of thesuspension lines. In other embodiments, the release line is attached tothe center line and then to the riser. The release line is shorter inlength than the combined length of the length of the tow line, the crownlines, the length of the portion of canopy that is in between the towline and the lower parachute lines, and the length of one lowerparachute line.

The release line is configured to actuate release 2104 under a secondthreshold force. Some examples of the release are described in moredetail with respect to FIGS. 15A to 18B. In some embodiments, the secondthreshold force is lower than the first threshold force (e.g., the firstthreshold force is the force to release the lower parachute linerestrainer). In some embodiments, actuation of the release allows theparachute and rocket to separate with little or no recoil.

FIG. 21E is a diagram illustrating an embodiment of a parachutedeployment system following separation of the parachute from the rocket.In this example, as part of the actuation of the release, each of thecrown lines individually release to minimize mass inhibiting inflationof the parachute. Although line constrainer 2120 is shown attached tothe release here, in other embodiments, the line constrainer may simplydetach and fall off. In the example shown, the rocket remains tetheredto the release. The rocket and release are separated from the parachuteand payload. In various embodiments, the release line and crown (tow)line remain attached to the canopy of the parachute. In someembodiments, the canopy completely fills following separation from therocket as shown in FIG. 21F.

Although in this example, crown lines 2108 are pictured as beingrelatively short, the crown lines may instead be sized of sufficientlength to allow full deployment of the parachute canopy without beingconstrained by the crown lines. For example, when the rocket and/orrelease malfunctions (e.g., rocket fails to release), the canopy is ableto completely fill because the crown lines are of sufficient length toallow the canopy to fully open. When a rocket release failure isdetected, a line constrainer (if one is used) slips axially upward tothe top of the crown lines, and crown lines are permitted to extend tofull length to facilitate full filling of the canopy. In other words,the crown lines extend without interfering with full inflation of thecanopy.

FIG. 21F is a diagram illustrating an embodiment of a parachutedeployment system with a fully deployed parachute. The end of parachuteextraction is sometimes called an “end stroke,” and the beginning of theparachute falling is called a “down stroke.” FIG. 21E shows a parachuteend stroke, and FIG. 21F shows a parachute down stroke. There is littleor no recoil on the end stroke. The line constrainer allows the level ofdamping of the end stroke to be controlled. In various embodiments, therelease line 2114 and crown (tow) lines 2108 remain attached to thecanopy 2110 of the parachute as shown.

In some embodiments, the extent to which crown lines are able to extendaway from a longitudinal axis of a parachute of a parachute deploymentsystem can be limited without a line constrainer. For example, fixedcrown line lengths produce a desired cross-sectional area withoutneeding to provide a line constrainer.

FIG. 23 is a flow diagram illustrating an embodiment of a process tomanufacture a parachute deployment system including a line constrainer.The process can be implemented by a parachute deployment systemassembler, such as a programmed robotic arm or by manual efforts. Theprocess can be used to manufacture a parachute deployment such as theone shown in FIGS. 19A and 19B.

At 2300, a parachute is coupled to a release via a first load path.Referring to FIG. 19A, parachute 1910 is coupled to release 1904 via afirst load path. The first load path is made up of crown lines 1908. Theparachute can be removably coupled to the release such that theparachute is separated from the release (and rocket) during parachutedeployment as described here. Examples of the release are shown in FIGS.15A-18B.

In various embodiments, coupling the parachute to the release includesassembling a parachute system (such as the one shown in FIGS. 19A and19B) for extraction via a load path through the upper parachute lines,canopy, and suspension lines, and for release via a release line. Therelease line length may be tuned so that substantially all tension istaken through the release line when the extraction load path isunconstrained. The suspension line restrainer size can be tuned to leaveample slack in the release line when the extraction load path is undertension.

Returning to FIG. 23, at 2302, a line constrainer is coupled between therelease and the parachute. The line constrainer restricts an extent towhich crown lines are able to extend away from a longitudinal axis ofthe parachute. The extension of the crown lines can be selected based ona desired level of extension damping. As more fully described withrespect to FIGS. 19A and 19B, greater extension of the crown linescorresponds to greater extension damping. In various embodiments, theline constrainer includes grommets through which crown lines areextended. One end of the crown lines is coupled to the release, and theother end of the crown lines is coupled to the canopy of the parachute.

The line restrainer is installed on the upper parachute lines above thecanopy, where the line constrainer is able to restrict an extension ofthe upper parachute lines radially outward away from the longitudinalaxis of the parachute system. In various embodiments, the components ofthe parachute system including the release are integrated withconnections and ties prior to packing the parachute into acontainer/can.

In various embodiments, the parachute deployment system is packed into acan. The parachute is stored in an un-deployed state, and is extractedin the sequence shown in FIGS. 11A-11F or FIGS. 21A-21F. The parachutecan be stored in a manner to promote quick inflation when deployed asdescribed with respect to the following figures.

In various embodiments, the parachute deployment system has features topromote airflow through a top of the canopy to speed up inflation of theparachute and decrease recoil. Air inflow through the top (canopy) ofthe parachute helps the parachute inflate quickly once the downwardstroke begins, without substantial dropping, by spreading the skirtduring the extension stroke. The manner in which the parachute is packedinto its can affects the speed of inflation. For example, a tightlypacked and rolled parachute inflates slowly and results in more altitudeloss during parachute inflation. The following figures illustrateexamples of how air inflow is promoted by packing the parachute in themanner described.

FIG. 24 is a diagram illustrating an embodiment of a conventionalparachute in a conventional packed state. In this example, the parachuteincludes upper parachute lines 2408, canopy 2410, and lower parachutelines 2412. The cross section at dashed line B1 is shown. The canopy mayhave vent lines or holes allowing air to pass through and providestability while the parachute is in flight. During a packing process,the parachute is then compressed and rolled into a cylindrical shape(e.g., where the parachute is rolled up like a sleeping bag or cinnamonbun) as shown in B1 (i.e., so that the hem is no longer loose). Althoughthis form of packing may be appropriate for conventional parachutes(e.g., without a line constrainer to constrain the upper parachutelines), this type of packing may be less than desirable for parachuteswith a line constrainer. The following figure shows an alternativepacking shape for such parachutes.

FIG. 25 is a diagram illustrating an embodiment of a parachute in asymmetrically packed state. Packing the parachute symmetrically is goodfor airflow down the center channel, symmetry as the parachute isextracted, and even loading as the parachute reaches full extension.Although not shown herein, in some embodiments the exemplary parachutesystem includes a line restrainer on its upper parachute lines. Thecross section at dashed line B2 is shown. As shown, there is an opening2530 that allows air inflow through the canopy. Due to the parachutemoving through the air as it is extracted, air is pumped through theparachute through the crown (a center channel of the canopy) tofacilitate inflation of the canopy as represented by the airflow arrows.

To help with airflow and more quickly inflate the parachute, theexemplary parachute is packed in an “M” cross-sectional shape designedto inflate quickly. The parachute is packed symmetrically with respectto a longitudinal axis of the parachute. Here, the longitudinal axiscomes out of the page, and parachute material is evenly distributedabout the axis to facilitate even loading upon extraction. By contrast,the packed parachute in FIG. 24 does not have an equal amount ofmaterial distributed around the longitudinal axis. Instead, most of themass is on top of the longitudinal axis, because the location of thecanopy apex is in the bottom layer of the rolled up parachute. Thus,when the parachute in FIG. 24 is extracted, loading is uneven and theparachute needs to unroll before air flows through a center channel ofthe canopy. This tends to make the inflation of the parachute relativelyslow, uneven, and unsteady. To put it another way, instead of rollingthe parachute (as shown in FIG. 24), the parachute is pulled and foldedtogether evenly from all directions toward the longitudinal axis beforebeing compressed in the can. In some embodiments, the hem remains looserather than rolled into the folds of the parachute. This symmetricpacking technique may be attractive for fast inflation when a vehicle isat low speed.

The rolling packing technique shown in FIG. 24 may be attractive when avehicle is at high speed to slightly delay opening, keeping the fabricorderly until the parachute aligns with the airstream. This may reduceincidences of inversion of the canopy, particularly when parachutes areoriented in the cans/packs such that only a single gore is exposed tothe airstream on extraction.

The following figures show examples of an exemplary parachute deploymentsystem with locking stows at various points in time. This system is analternative to the one with a slider release shown in FIGS. 21A-21F.This system may be particularly attractive for higher altitudes (forexample above 100 ft) and for higher speeds (for example above 25 mph)because it allows greater altitude loss during parachute inflationbefore touchdown. The system does not require a release and accompanyingcomponents such as a release line and line constrainer.

The bag/sleeve shown in the following figures stays with the parachutecanopy in the early stages of extraction and a riser line and suspensionlines are pulled through a stow to separate the rocket from the canopy.

FIG. 22A is an exploded view illustrating an embodiment of a parachutedeployment system with locking stows. Each of the lines are depicted asfully extended for purposes of clearly illustrating each of the parts.In various states of deployment as shown below, the lines may be folded.The system includes rocket 2200, rocket tow line 2202, parachute 2210,deployment bag or sleeve 2240, lower parachute lines 2212, riser 2217,and payload 2250 (such as the vehicle shown in FIG. 2). Each of thecomponents are like their counterparts in FIG. 21A unless otherwisedescribed.

Deployment bag 2240 is adapted to hold parachute canopy 2210. Theparachute can be packed into the bag in a variety of ways including theexamples shown in FIGS. 11A and 24-27. The canopy 2210 is secured insidethe deployment bag using one or more locking stows in a way that thecanopy does not initially fall out of the deployment bag. When rocket2200 reaches a threshold distance from the payload, the rocket pullssuspension lines 2212 and riser 2217 so that they are extended, a flapin the bag opens, and the rocket and deployment bag separates from thecanopy 2210.

The following figures show the portion of the system of FIG. 22A withinthe dashed oval to illustrate operation of the system.

FIG. 22B is a diagram illustrating an embodiment of a parachutedeployment system with locking stows when a rocket is initiallydeployed. Initially, lower parachutes lines 2212 are packed insidedeployment bag 2240 while riser 2217 dangles from the flap enclosing thedeployment bag. The lower parachute lines 2212 can be coiled and securedwith rubber bands (as an example) using a variety of techniques to forma locking stow.

Rocket 2200 begins traveling away from deployment bag 2240 (here,substantially up), causing lower parachutes lines 2212 and riser 2217 toextend. The lower parachute lines can extend outside the bag viaopenings 2242. The openings form part of a locking stow that initiallyhold the canopy and at least a portion of the lower parachute linesinside the deployment bag. Later, when conditions are met, the lockingstow will unlock and the bottom of the deployment bag will open topermit the bag and rocket to separate from the canopy. Conditions mayinclude a threshold distance between the rocket and the payload or aknown length of suspension lines having exited the bag. The lockingstows can be designed with materials, dimensioning, etc. to unlock underdesired conditions.

FIG. 22C is a diagram illustrating an embodiment of a parachutedeployment system with locking stows during extraction. In this state ofdeployment, rocket 2200 continues traveling away from the payload (here,substantially higher) compared with FIG. 22B. Consequently, lowerparachute lines 2212 and riser 2217 are more extended. A portion of thelower parachute lines has been pulled through the openings of thedeployment bag and are now outside deployment bag 2240. As the rockettravels farther away from the payload, locking stows begin tounlock/break. At least one of the locking stows remains locked in thisstate.

FIG. 22D is a diagram illustrating an embodiment of a parachutedeployment system with locking stows at the later stages of extraction.In this state of deployment, rocket 2200 continues traveling away fromthe payload, and the final locking stow has broken free creating anopening in the deployment bag to allow the canopy to begin exiting fromthe bag. The dashed portion of the deployment bag is a flap thatinitially (FIG. 22B) covers the opening of the bag and now is danglingfrom a portion of the bottom of the bag. Rocket 2200 will continue totravel away from the payload to continue extending the lower parachutelines 2212 and riser 2217. The extending lower parachute lines and riserpull the canopy away from the deployment bag 2240.

FIG. 22E is a diagram illustrating an embodiment of a parachutedeployment system with locking stows after the rocket separates from theparachute. In this state of deployment, rocket 2200 and deployment bag2240 have separated from the canopy. Canopy 2210 of the parachute isfully inflated, parachute lines 2212 and riser 2217 are pulled taut, andthe canopy is arresting the fall of payload (2250 of FIGS. 22A).

This extraction technique can be used in combination with other oneslike the one described in FIGS. 21A-21F. For example, one (or more)parachute(s) in a multi-parachute system can be extracted this way whileother ones of the multi-parachute system are extracted using othertechniques. A first or drogue parachute may be extracted using thistechnique because the aircraft is at a relatively higher altitude andspeed, and when the aircraft is at a lower altitude and speed theextraction technique described in FIGS. 21A-21F may be more attractive.

The following figures show an example of a canister in which parachutesare packed. The canister contains a deployment bag or sleeve 2240. Thesoft pack can be embedded behind the cockpit of a multicopter as shownin FIG. 6.

FIG. 26 is a diagram illustrating an embodiment of a soft pack containerfor a parachute. This soft pack container may be attractive for avariety of reasons including being able to reduce the packed volume of aparachute and maintaining pressure on the packed parachute withoutinterfering with the extraction process, being easy to mount on avehicle, and being more durable and less likely to be damaged becausemetallics are separated from the parachute.

The soft pack container is made of a soft material (unlike hard-sidedcontainers such as metal or hard plastic canisters), which allowspressure to be maintained on the packed parachute using lacing system2650. The container has four side walls and a bottom forming a cavity2610 to receive a parachute. The four side walls and bottom can be oneor more separate fabric panels stitched together at the seams as shown.The top of the container has four flaps that can be folded over andslightly overlapped to enclose the cavity 2610. The flaps can be held inplace using a locking stow (not shown), which is further described inFIG. 27. In the state shown, each of the flaps (an exemplary one is flap2614) is folded down so that the top is open and the cavity is exposed.

The container includes a lacing system 2650, which is shown here withoutthe lace. The eyelets are configured to receive the lace, which can bepassed through the eyelets to compress the soft pack to a desired size.Unlike a hard canister whose walls do not yield to compression, the softpack shown here can maintain a tight pack volume by cinching the packusing the lacing system to a desired volume. When a rocket is deployed,the parachute can be pulled through the pack when conditions are met tounlock the locking stow as further described in FIG. 27. This allows theparachute to be easily extracted. In addition, a locking stow forclosing the flaps can also help to maintain pressure on the pack.

The container includes mounting grommets (shown in FIG. 27), which allowthe container to be mounted to a vehicle such as the one shown in FIG.2. The container also includes a pocket 2604. Components of theparachute system that might damage the canopy such as metallic, releasedevices, and the like can be separated from the canopy by being placedin the pocket to avoid damaging the canopy. The lacing system and pocketcan be placed on any side of the pack and their example positions hereare not intended to be limiting.

Some elements of the soft pack are not shown here for purposes of moreclearly illustrating the container. The following figure shows the softpack container with a parachute packed inside and rocket attached. Thesystem is ready for deployment, and can be provided in an aircraft asshown in FIG. 2.

FIG. 27 is a diagram illustrating an embodiment of a soft pack containerfor a parachute in a packed state. Each of the components are like theircounterparts in FIG. 26 unless otherwise described. Here, the parachuteis inside the cavity formed by the walls of the soft pack and secured inplace by the folded flaps 2710, 2712, 2714, and 2716 via a locking stow2742. The locking stow may be implemented in the same way as the lockingstows described elsewhere in this disclosure. A lace can be threadedthrough the eyelets to form lacing system 2750 as shown. The lacingsystem can be tightened or loosened depending on a desired amount ofpressure or packed size. Mounting grommets 2706, 2708, and 2728 can beused to attach the soft pack to a vehicle.

In this example, a rocket 2700 is attached to the soft pack via a bridle2702. During an extraction process such as the one shown in FIGS.22A-22E, the rocket deploys away (e.g., upwards), pulling the bridle andwith it the contents of pocket 2704. When the rocket reaches certainconditions such as when a threshold force is exerted, the locking stowunlocks and the parachute is extracted from the soft pack.

The various embodiments of the disclosed system are capable ofrecovering a payload (e.g., an attached aircraft or person) at lowaltitude and low speed conditions and are also adaptable to high speedor high altitude conditions. The parachute deployment system tolerateshigh loads during initial extraction of the parachute, but actuatesrelease of the rocket with a low load and low recoil. The disclosedsystem may be packed into a small space and is low in mass. In someembodiments, the disclosed parachute deployment system tolerates chaoticextraction and is agnostic to rotation.

Although the foregoing embodiments have been described in some detailfor purposes of clarity of understanding, the invention is not limitedto the details provided. There are many alternative ways of implementingthe invention. The disclosed embodiments are illustrative and notrestrictive.

What is claimed is:
 1. A system to deploy a plurality of parachutes,comprising: a plurality of parachute canopies each packed in a canister;a plurality of rockets adapted to extract an associated canopy from thecanister; and a controller configured to: determine that an aircraft isat least one of: in a hover mode of operation and a forward flight modeof operation; in response to the determination that the aircraft is inthe hover mode of operation, apply a hover deployment sequence includinginstructing the plurality of parachutes to deploy substantiallysimultaneously; and in response to the determination that the aircraftis in the forward mode of operation and above a threshold airspeed,apply a forward deployment sequence including instructing the pluralityof parachutes to deploy in a predefined sequence.
 2. The system of claim1, wherein the controller is configured to instruct the rockets todeploy such that a lower vehicle system does not exceed a thresholdimpact velocity.
 3. The system of claim 1, wherein the system isprovided behind a cockpit of a vehicle.
 4. The system of claim 1,wherein one of the plurality of canopies is a drogue parachute canopyconfigured to be extracted prior to the other ones of the plurality ofcanopies.
 5. The system of claim 1, wherein each of the plurality ofcanopies is connected by an independent line to a connection pointbehind a headrest in a cockpit of the aircraft.
 6. The system of claim5, wherein the connection point is part of a frame of a fuselage.
 7. Thesystem of claim 1, wherein the plurality of canisters are arranged in atriangular formation with at least one of the plurality of canisterspositioned closer to a tail of the aircraft than at least two others ofthe canisters.
 8. The system of claim 1, wherein: at least one of theplurality of canopies is coupled to an associated rocket via a firstload path, the first load path including a tow line, at least one upperparachute line, at least one lower parachute line, and a second loadpath including a release line; and at least one of the plurality ofrockets is adapted to tow the associated canopy via the tow line.
 9. Thesystem of claim 8, further comprising a lower parachute line restrainerwhich when released permits the at least one lower parachute line toextend to full length.
 10. The system of claim 8, further comprising arelease configured to open in response to a load switching from thefirst load path to the second load path, wherein when the release isopen, the associated canopy and the associated rocket are permitted toseparate.
 11. The system of claim 1, wherein at least one of thecanisters is a deployment bag with a locking stow adapted to close flapsof the deployment bag and the locking stow is configured to unlockpermitting the associated canopy to separate from the deployment bag.12. The system of claim 1, wherein at least one of the canisters is adeployment bag including: a lacing system adapted to maintain pressureon the deployment bag; a pocket adapted to separate the associatedcanopy stored in the deployment bag from other components of in thedeployment bag; and at least one mounting grommet for attaching thedeployment bag to the aircraft.
 13. A method to deploy a plurality ofparachutes, comprising: receiving an indication to deploy a parachutesystem from a flight computer; determining that an aircraft is at leastone of: in a hover mode of operation and a forward flight mode ofoperation; in response to the determination that the aircraft is in thehover mode of operation, applying a hover deployment sequence includingdeploying the plurality of parachutes substantially simultaneously; andin response to the determination that the aircraft is in the forwardmode of operation and above a threshold airspeed, applying a forwarddeployment sequence.
 14. The method of claim 13, wherein the flightcomputer determines the indication to deploy the parachute system basedat least in part on an anticipated crash landing, hard landing, orfault.
 15. The method of claim 13, further comprising determining thatthe aircraft is in the hover mode of operation based at least in part onthe aircraft's airspeed being below the threshold airspeed.
 16. Themethod of claim 13, further comprising determining that the aircraft isin the hover mode of operation based at least in part on the aircraft'sforward speed or lateral speed being substantially zero.
 17. The methodof claim 13, wherein the forward deployment sequence includes deployingat least one of the plurality of parachutes prior to deploying otherones of the plurality of parachutes.
 18. The method of claim 17, whereinthe forward deployment sequence includes: deploying the at least one ofthe plurality of parachutes; waiting for the aircraft to stabilize; anddeploying at least one rocket associated with another one of theplurality of parachutes, wherein a trajectory of the at least one rocketis configured to clear a vertical axis and canopy under which theaircraft is hanging.
 19. The method of claim 13, wherein all canopiesassociated with the plurality of parachutes are fully extracted beforeany one is fully inflated.
 20. A system to deploy a plurality ofparachutes, comprising: container means for holding a respectiveparachute canopy in a packed state; deployment means for extracting anassociated canopy from the container means; and controller means for:determining that an aircraft is at least one of: in a hover mode ofoperation and a forward flight mode of operation; in response to thedetermination that the aircraft is in the hover mode of operation,applying a hover deployment sequence including instructing the pluralityof parachutes to deploy substantially simultaneously; and in response tothe determination that the aircraft is in the forward mode of operationand above a threshold airspeed, applying a forward deployment sequenceincluding instructing the plurality of parachutes to deploy in apredefined sequence.